A supporter of gay marriage waves a rainbow flag outside the Massachusetts State House, where the Legislature was in its second day of debate over a possible constitutional amendment banning same-sex marriage on February 12, 2004, in Boston.

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It’s hard to believe today, when the vast majority of Americans support it, but just 20 years ago the issue of same-sex marriage divided the country and drove voter turnout.

The vast majority of Americans opposed same-sex marriage on May 17, 2004, when the first same-sex couples took their vows after a court decision in Massachusetts.

The state’s Republican governor at the time, Mitt Romney, planned to invoke an archaic 1913 law in an attempt to bar same-sex couples from traveling from other states to obtain marriages in Massachusetts.

Then-President George W. Bush, a Republican running for reelection, gave an address from the White House that year actively pushing to amend the US Constitution to “protect” marriage, which he described as “the most fundamental institution of civilization.”

There was verifiable backlash to marriage equality in November 2004, when voters in 11 states – ranging from reliably red Utah to reliably blue Oregon – codified in their constitutions that marriage should be between a man and a woman.

Hillary, right, and Julie Goodridge, left, lead plaintiffs in the Massachusetts gay marriage lawsuit, get married at Boston City Hall on May 17, 2004.

The marriage amendment approved in Ohio by an overwhelming majority may have helped sway that pivotal state into Bush’s column as he retained the White House. The effort to oppose same-sex marriage certainly didn’t hurt him in the state. Without Ohio, Bush would have lost to then-Sen. John Kerry, the Massachusetts Democrat who opposed same-sex marriages taking place in his own state.

The 2015 Supreme Court case, Obergefell v. Hodges, by which a divided 5-4 court would ultimately grant a right to same-sex marriage, sprang up as a result of this Ohio amendment.

In CNN exit polls for the presidential election in 2004, just a quarter of all American voters that year said they supported marriage rights for same-sex couples. A larger proportion, 35%, supported giving same-sex couples the ability to enter into civil unions. And 37% opposed legal recognition of same-sex unions.

Barack Obama notably opposed same-sex marriage when he ran for president as a Democrat in the 2008 election and, as public opinion was rapidly shifting, changed his tune in 2012 to support same-sex unions.

In eight years, the US went from the winning candidate (Bush in 2004) exploiting opposition to same-sex marriage to win reelection, to the winning candidate (Obama in 2012) changing his position to support marriage equality before winning reelection.

Now, it’s Congress protecting same-sex marriage from the Supreme Court

A decade later, in 2022, the person Obama beat in 2012, now-Sen. Romney, voted in favor of protecting same-sex unions in the event the US Supreme Court decided to strip away the national right to marry that it granted in 2015.

The court today is much more conservative than it was in 2015 after two justices who supported same-sex marriage rights, Justices Anthony Kennedy and Ruth Bader Ginsburg, were replaced with Justices Brett Kavanaugh and Amy Coney Barrett, respectively.

Two current conservative justices, Clarence Thomas and Samuel Alito, still publicly grouse about the Obergefell decision, but it’s not clear if an opportunity to overturn the decision will present itself or if the conservative justices who weren’t on the court in 2015 would support removing the right to same-sex marriage in the same way they endorsed removing a right to abortion.

Romney does not now support same-sex marriages, but he made clear when he voted to protect them from the Supreme Court that he does respect people who have entered into them:

“While I believe in traditional marriage,” Romney said in a statement, “Obergefell is and has been the law of the land upon which LGBTQ individuals have relied. This legislation provides certainty to many LGBTQ Americans, and it signals that Congress—and I—esteem and love all of our fellow Americans equally.”

The Respect for Marriage Act that Romney supported does not guarantee a national right to same-sex marriage if the Supreme Court changes course, but it does require every state to honor marriages conducted legally in other states.

If the Supreme Court overturned Obergefell, most states still have laws and constitutional amendments that ban same-sex marriage, according to an analysis by Stateline.

‘Stunning’ reversal

The annual American Values survey conducted by PRRI in 2023 found a strong majority of Americans – more than two-thirds – now support same-sex unions, but the support varies. In states that protect same-sex marriage regardless of Obergefell, support is over 70%. Support falls to 64% in states where same-sex marriage would end without Obergefell.

I talked to Alex Lundry, a Republican pollster and longtime supporter of same-sex marriage, about how he views this 20-year pivot in public opinion.

“It’s stunning in its reversal,” Lundry said, adding, “in my opinion, it’s the most significant and substantial shift in public opinion of the modern polling era.”

20% of Gen Z identifies as LGBTQ

Lundry pointed to a series of data points to explain the overwhelming shift in public opinion:

► First, more people identify as LGBTQ. He pointed to data from Gallup, which saw the portion of the population who identify as LGBTQ more than double from 3.5% in 2012, when the organization first started asking people about their sexual orientation, to 7.2% 2022, the last year for which it has data.

► More importantly, maybe, is that almost 20% of Gen Z Americans, those born between 1997 and 2004, identify as LGBTQ, with most of them identifying as bisexual.

► As a result, more people know and care about someone who is gay. That trend was already underway back in 2004, when Bush’s vice president, Dick Cheney, one of whose daughters is gay, openly disagreed with the push for an anti-same-sex marriage constitutional amendment. Today there is far more representation of gay outlooks in the media and in government, where the organization Out for America, which tracks representation, found the number of openly LGBTQ lawmakers rose from less than 500 in 2017 to nearly 1,200 in 2023.

► Underlying all of that is that the number of same-sex couples has more than doubled from less than 600,000 in 2008 to more than 1.2 million in 2021, roughly 710,000 of which are married, according to Census Bureau data.

Warnings were unfounded

There is also evidence that warnings about same-sex marriage somehow endangering “traditional marriage” simply never materialized.

A new study by researchers for the RAND Corporation to assess two decades of same-sex marriage in the US argues marriage rates actually increased among opposite-sex couples as same-sex couples were granted the ability to marry in certain states. Physical health also improved in those states for same-sex couples, according to the study.

Another societal shift

Abortion rights are another social issue politicians hope to use to move the coming election. A key difference between support for same-sex marriage and support for abortion rights, according to Lundry, is that support for abortion rights has remained positive for decades, in contrast to same-sex marriage, which saw a complete turnaround.

The only other issue where he argued there has been such a pivot is on legalizing marijuana, support for which has gone from about a third in 2002 to 70% in 2023, according to Gallup.

Not at all coincidentally, President Joe Biden has moved in this election year to reclassify cannabis from a Schedule I drug to a Schedule III drug, acknowledging there are legitimate uses for it and making the government view it as a substance with a lower risk for abuse.

Meanwhile, the ever-evolving fight over LGBTQ rights continues. An issue driving state legislatures today is transgender rights, particularly regarding children and gender-affirming care.